[Bug target/72736] warning: switch -mcpu=cortex-a53 conflicts with -march=armv8-a switch

["jgreenhalgh at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72736

--- Comment #5 from James Greenhalgh <jgreenhalgh at gcc dot gnu.org> ---
(In reply to Jeffrey Walton from comment #4)
> Thanks, and sorry to waste your time with it.
> 
> Before I spin up another report that wastes a lot time, does this look like
> another issue with me (likely), or an issue with GCC (unlikely):
> 
> internal compiler error: in expand_shift_1, at expmed.c:2318
>    result = (r1 != r2);
> 
> Here's a quick copy/paste of the relevant pieces. I'll do the minimal
> working example if needed.
> 
> 
>     // Executed with a sig_handler guard
>     volatile bool result = true;
>     ...
> 
>     const poly64_t a1={1}, b1={2};
>     const poly64x2_t a2={1}, b2={2};
>     const poly128_t r1 = vmull_p64(a1, b1);
>     const poly128_t r2 = vmull_high_p64(a2, b2);
> 
>     result = (r1 != r2);

Internal compiler errors are almost never *your* fault, the compiler should
gracefully handle most of what you throw at it. If you can build a minimum
working example that would be handy (though note that GCC 4.9 is getting old
now, and the branch is due to close permanently in the very near future, so
unless this reproduces on 5/6/trunk we're probably past the point where it
would get looked at and fixed).